1. Field of the Invention
The present invention relates to new methods and new materials for measuring the effectiveness of biological decontamination and sterilization processes, and thus, relates to new methods and new materials for quality control assurance in biological decontamination and sterilization systems. More particularly, the present invention relates to new methods and new materials for effective, simple and routine quality control assurance in biological decontamination and sterilization systems that utilize at least one step involving physical disruption of treated wastes, where such physical disruption would destroy conventional, non-destruction-resistant quality control means, the present invention providing materials and methods for quality control that are resistant to physical disruption in biological decontamination and sterilization systems. Still more particularly, the present invention relates to the use of any biological organism, seeded on any destruction-resistant medium, used as a quality control means for any type of decontamination and/or sterilization procedure that would otherwise destroy a traditional, nondestruction-resistant quality control means.
2. General Background
Each year hospitals, laboratories, clinics and medical offices produce hundreds of thousands of tons of biomedical, infectious wastes. The safe, effective and inexpensive disposition of this waste has become a major issue of the late twentieth century. Ineffective and inappropriate disposal practices have led to dangerous and highly publicized incidents such as the discovery of infectious medical waste washed up on beaches of oceans and lakes, as well as well as the discovery of infectious wastes in ordinary trash containers in public areas. In response to such incidents, federal and state governments have acted to tightly regulate the disposition of infectious wastes, including the imposition of requirements mandating quality control assurances for biological waste treatment systems.
Historically, most infectious waste has been treated by incineration. However, recent studies performed on emissions generated from the combustion of medical waste, even from facilities equipped with advanced air pollution control equipment, have demonstrated consistent emission of priority metals, acid gases, and carcinogenic organics such as 2, 3, 7, 8 furans and dioxin. (United States Environmental Protection Agency, Hospital Waste Combustion Study, December, 1988), Such emissions from incineration have given rise to problems concerning compliance with the Federal Clean Air Standards Act which, as a result, have often raised to prohibitive levels capital and operating costs associated with incineration of biomedical wastes. Further, increased public awareness and opposition to incineration, especially in populous areas, and stricter licensing requirements have made many infectious waste generators, and their regulators, reexamine their options for the treatment and disposal of infectious medical and laboratory waste. (See, e.g., P. R. Murry, EIC, Manual of Clinical Microbiology, Sixth Ed., pgs. 92-93).
Another method traditionally used for decontamination of infectious wastes involves steam sterilization in autoclaves. However, autoclaves are not appropriate for economically treating large volumes of infectious waste. Further, additional complications with traditional steam sterilization techniques often arise because traditional steam sterilization techniques do not physically disrupt the treated waste. For example, the effectiveness of steam sterilization can be adversely affected by the physical nature of the waste to be treated (since the effectiveness of steam sterilization depends upon factors such as the density, physical state and size, and organic content of the waste), leading to problems in assuring effective quality control where autoclaved wastes are not physically disrupted. And, because autoclaves do not change the inherent visual appearance of treated waste, uncertainty and fear frequently arises among persons responsible for handling the treated waste, leading to, inter alia, many reported cases of autoclaved waste being rejected at landfills.
Hence, there is a need to develop alternative infectious waste disposal systems and technologies that solve, or reduce the problems presented by the traditional treatment systems of incineration and non-disruptive steam sterilization. To meet this need, the waste disposal industry developed a number of alternative infectious waste disposal systems that utilize a step of physical disruption of the waste as part of the treatment. Alternative waste disposal systems utilizing physical disruption steps avoid the pitfalls of both traditional non-disruptive, steam sterilization and incineration by both, respectively, i) enhancing the effectiveness of steam disinfection and sterilization and the identification of the treated product, and ii) eliminating dangerous emissions from waste incineration. (P. R. Murry, EIC, Manual of Clinical Microbiology, Sixth Ed., pgs. 93).
Some of the first alternative waste treatment systems produced involve mechanical-chemical treatment of infectious waste. Systems such as Medical SafeTEC, Inc.'s (Indianapolis, Ind.) Model Z1200 employ a high-speed hammer mill combined with a shredder to pulverize and shred waste material prior to exposing the waste to chemical decontamination agents such as sodium hypochlorite. In these systems, once shredded and pulverized, the waste is mixed with a decontaminant in hoppers and/or screw agar conveyors where it is treated and subsequently dried. The final, treated waste product consists of the decontaminated, shredded and pulverized waste in a dry or fluid-expressed state.
Other alternative infectious waste treatment systems utilize mechanical disruption combined with traditional steam sterilization. For example, the Roland biomedical waste treatment system, S.A.S.-1, (S.A.S. Systems, Inc., Houston, Tex.) shreds and then sterilizes infectious waste in an enclosed unit that operates as an autoclave and shredder. Other alternative infectious waste treatment systems utilizing mechanical and thermal treatment shred waste and then disinfect it with alternative sources of heat, such as, for example, dry heat (BioMed Continuous Thermal Disinfection Unit, BioMed Waste Systems, Inc., Boston, Mass.), microwaves (ABB Sanitec Microwave Disinfection System, ABB Environmental Services, Inc., Roseland, N.J.), and low frequency radio waves (Stericycle Electrothermal Deactivation System, Stericycle, Inc., Deerfield, Ill.). In all these cases, the final, treated waste product consists of decontaminated, shredded waste in a dry or fluid-expressed state.
Monitoring the effectiveness of disinfection in infectious waste disposal systems is, of course, of paramount importance. Numerous state and federal regulations address the need for both diagnosic and routine quality control in biological decontamination systems. (See Id.) However, prior to the instant invention, quality control systems for routine use in biological decontamination systems were designed for use only with the traditional non-destructive decontamination and sterilization means discussed above. Importantly, these traditional quality control means were, and are, not resistant to physical disruption. As a result, traditional quality control means are incompatible with newer, waste-disrupting decontamination means since, in practice, such means are destroyed in the treatment process when the waste is treated with the physical disruption step(s).
Traditional, nondestruction-resistant quality control means for steam sterilization include, for example, glass and/or plastic ampules. (See, for example, Attest Biological Indicator, manufactured by 3M Health Care, St. Paul, Minn. 55144-1000. These ampules contain a given number of viable microorganisms either in vegetative state, or, as heat resistant endospores. As a means of routine quality control, an ampule is added to the waste to be treated. After treatment, the ampule is recovered, activated and the contents cultured. A determination of the viability of the contents of the ampule post sterilization and/or decontamination provides the means for quality control.
While these ampule-type means for quality control work well for traditional nondestruction-type waste treatment systems, they are wholly incompatible with modern destruction-type waste treatment systems. This is because the fragile ampule would be broken open during processing of the waste, making it impossible to recover the contents for subsequent determination of viability. Further, because modern waste disposal systems frequently treat continuous streams of waste, rather than batches, and because the waste is mixed upon treatment, it would be difficult, if not impossible to locate an ampule in the waste stream, even if it managed to remain uncrushed during treatment.
Another type of traditional, nondestruction-resistant quality control means for steam sterilization includes, for example, a small strip of material impregnated with bacterial spores. See, for example, SPORDEX.RTM.-SPORDI.RTM. Biological Indicators, manufactured by AMSCO International, Apex, N.C. 27502. These small strips of material contain a given number of viable microorganisms impregnated on the medium as heat resistant endospores. As a means of routine quality control, an impregnated strip of material is added to the waste to be treated with steam. After treatment, the material is recovered and cultured. A determination of the viability of the contents of the strip post sterilization and/or decontamination provides the means for quality control.
While these impregnated strip-type means for quality control work well for traditional nondestruction-type waste treatment systems, they, like ampules, are also wholly incompatible with modern destruction-type waste treatment systems. This is because the strips would be lost and/or torn into pieces during processing of the waste, making it impossible to recover the contents for subsequent determination of viability. Further, as with ampules, because modern waste disposal systems frequently mix waste upon treatment, it would be difficult, if not impossible to locate a small strip in the treated waste stream.
Thus, while the advent of alternative infectious waste treatment systems involving physical disruption of waste has brought an answer to many of the problems posed by traditional waste treatments, prior to the instant invention, there remained a great need for an accurate, simple and inexpensive means for providing routine quality control for these new waste-disrupting treatment systems. (See, e.g., Technical Assistance Manual: State Regulatory Oversight of Medical Waste Treatment Technologies, April 1994, A Report of the State and Territorial Association on Alternate Treatment Technologies, pg. 1).
In this article, inter alia, recognizing the need for quality control in non-traditional disruptive-type alternate medical waste treatment technologies, the several states that had actively participated in programs authorized under the federal Medical Waste Tracking Act of 1988 organized into an association known as the State and Territorial Association on Alternate Treatment Technologies ("Association"). In 1994, the Association produced the Technical Assistance Manual: State Regulatory oversight of Medical Waste Treatment Technologies, which is hereby incorporated by reference in its entirety. This manual outlines both the need for quality control in "alternate" waste treatment systems ("alternate" being defined as "other than non-destruction-type steam sterilization or incineration," see pg. 1) and goals for quality control assays.
The manual sets forth, inter alia, i) a definition of the level of recommended microbial inactivation; ii) establishment of defined pathogen surrogates for microbial inactivation evaluation (including vegetative pathogen surrogates and bacterial spore formers); iii) formulae for enumeration for efficacy testing protocol quantification; and iv) development guidelines for approval of specific treatment processes and specific testing protocols.
However, and significantly, the manual was unable to propose specific recommended methods and materials for routine quality control in "alternate" (destruction-type) waste disposal systems. Instead, and in recognition of the long felt but unresolved need for such quality control means, the manual implored workers in the technical field to try to conceive of a workable, destruction-resistant quality control means (like the instant invention) for non-tradition decontamination systems.
While, as discussed in more detail below, the manual recognized the need for a destruction-resistant means to easily and routinely quantitate the effectiveness of alternate decontamination procedures, and the manual proposed microorganisms to be used with such procedures, guidelines to be followed when practicing such procedures, and goals of such procedures, importantly, the manual was unable to propose or suggest a suitable destruction resistant material and method for routine use.
In answer to the needs of the prior art, and those emphasized by the Alternate Treatment Technologies manual, the instant invention provides methods and destruction-resistant materials for inexpensive, simple and routine analysis of quality control of biological decontamination and sterilization systems utilizing alternative infectious waste disposal systems that physically disrupt waste upon treatment.
Briefly, the instant invention relates to a novel method and a product for quality control in alternative, destruction-type biological decontamination and sterilization processes. The invention relates the use of a biological organism, seeded on any destruction-resistant medium, used as a quality control means for any type of decontamination and/or sterilization procedure that would otherwise destroy a traditional, nondestruction-resistant quality control means. In one embodiment of the invention, for example, destruction-resistant sponges seeded with in a known number and type of bacteria, or spores, are used as a routine quality control means for alternate biological decontamination and/or sterilization processes. In such an embodiment, the bacteria/spore-seeded destruction-resistant sponge is added to the waste to be treated and then is processed along with the waste. The sponge material is then recovered from the treated waste where it can easily be visually and/or tactilely identified and removed from the waste stream. Following established protocols, (for example, those outlined in the Oversight of Medical Waste Treatment Technologies Manual) the number of viable bacteria associated with the recovered sponge material is determined (for example, by culturing and quantitating the number of viable organisms recovered) and compared relative to an untreated, control sponge and/or the sponge before treatment. A calculation of the reduction in viable bacteria between the seeded sponge and the treated sponge is then used to easily assess (again, for example, as per the guidelines of the Technical Assistance Manual) the quality, or effectiveness, of the biological decontamination process. In another similar embodiment, a destruction-resistant sponge seeded with a known number and type of microorganisms is added to a waste treatment system and recovered post treatment, and then the recovered sponge is cultured for the presence of any growth of the seeded organisms; the results producing an all-or-none qualitative evaluation of the effectiveness of the waste decontamination and/or sterilization system. Further descriptions of the preferred embodiments of the present invention are discussed below in the section entitled Detailed Description of the Preferred Embodiment.
While other patents have disclosed the assaying of waste treated by alternative destruction-type decontamination processes, these have been only for one-time-only/non-routine means of determining the efficacy of such systems, no known patents, or other publications, disclose the instant invention's use of an organism-seeded destruction-resistant material for carrying and recovery of "seed" organisms as a convenient, inexpensive and routine test for quality control in decontamination and/or sterilization procedures that physically disrupt the treated waste.
U.S. Pat. No. 5,372,929 to Cimino et al. discloses methods for measuring pathogen inactivation particularly in blood and blood products after photochemical decontamination. The measuring methods disclosed in the patent are drawn toward biochemical tests of the inhibition of template-dependent enzymatic synthesis. The Cimino et al. patent discloses a very different means for measuring the inactivation of organisms than does the instant invention. Further, the Cimino et al. patent appears drawn only to use with small scale decontamination processes, such as the decontamination of blood and blood products. Unlike the instant invention, it appears unlikely that the method of Cimino et al. would be practical for measuring inactivation of pathogens in large scale decontamination processes, such as the decontamination of hospital wastes.
U.S. Pat. Nos. 5,078,965 and 5,077,007 to Pearson disclose a process and apparatus for the batch treatment of infectious waste material in a fluidized bed reactor utilizing gas oxidation. While the patents disclose the use of a pretreatment inoculum of a know number and type of infectious organisms, and the subsequent culturing and enumeration of the organisms that are left after treatment as a means of determining the biological inactivation, the patents do not disclose the instant invention's means of providing a bacteria-seeded sponge for routine quality control of decontamination processes. The patents also fail to disclose the instant invention's ease of recovery of the seeded organisms. Further, the patents only disclose the removal of "seed" organisms from the liquid state of the wastes; no quality control is disclosed for checking the final "dewatered" residue.
U.S. Pat. Nos. 5,116,574 and 5,173,257 to Pearson disclose a process and apparatus for continuously treating infectious waste. Like U.S. Pat. Nos. 5,078,965 and 5,077,007 issued to Pearson and discussed above, U.S. Pat. Nos. 5,116,574 and 5,173,257 disclose only the experimental use of a liquid inoculum of infectious organisms. The patents fail to disclose the use of an organism-seeded sponge for routine quality control in decontamination processes.
U.S. Pat. No. 5,322,603 to Kameda et al. discloses a method of treating medical wastes with microwaves and hot air. Significantly, this patent discloses no means for assuring, or detecting, the killing of infectious organisms during the decontamination process.
U.S. Pat. No. 5,348,235 to Pappas discloses a medical waste disposal system wherein medical wastes are superheated such that no known pathogens can survive the operating temperatures of the system. Significantly, unlike the instant invention, the Pappas patent discloses no means for assuring, or detecting, the killing of infectious organisms during the treatment process.
Thus, while there is a recognized need in the field for a simple and economical means for routine quality control in alternate biological decontamination systems, issued patents related to alternative medical waste disposal systems do not disclose such a means. In fact, the only method for assessing effectiveness of alternative waste decontamination systems disclosed in the patents (other than the technically complex template-dependent enzymatic synthesis method of Cimino et al.) is the cumbersome assay method of providing a liquid inoculum with a known number of microorganisms to a defined batch of waste to be treated, treating the batch and then removing liquid samples from the treated liquid. Such protocols are difficult to perform, are not highly reproducible (due to the great dilution of recovered inoculum), cannot be used to evaluate dried (or liquid expressed) waste product (the actual waste product of the majority, if not all, commercial alternative waste treatment systems), and are not compatible with continuous run systems (the use of a liquid inoculum requires a treatment of a single batch of waste, rather than a continuous stream of waste as utilized in most alternate waste treatment systems).
Thus, as evidenced by both issued patents in the field and technical publications in the field, there is a need for a simple, economic and routine quality control method and means for use with alternative type, destruction-type medical waste treatment technologies.